P16 overexpression in pituitary adenomas studied by immunohistochemistry and in situ hybridization

Objectives To examine the expression of p16 gene and the clinicopathologica l characteristics of 31 pituitary adenomas, To investigate the relationship between p16 expression and cell proliferative activity by analyzing the ex pression of proliferating cell nuclear antigens (PCNA). Methods Immunohistochemistry and in situ hybridization were performed on fr eshly-prepared paraffin-embedded adenomas. performed specimens of 31 pituit ary. Results Varying degrees of overexpression of the p16 gene was found in the tumors specimens. A higher proportion of p16 positive tumor cells was assoc iated with bigger size, more frequent invasion and higher recurrence of the tumors. The expression of p16 was found to be significantly associated wit h the degree of PCNA expression. Conclusion Though inactivation of the p16 gene is known in wide range of tu mors, our study suggested that p16 overexpression might play a role in the development and progression of pituitary adenomas.